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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'de499c71abe8bf3317d82414c4f9dc4dd4cc07e8d8a3f601de6699a7cba246e8' 
  AND token = 'Unj7LzIa7RwSRsglrRd7f7dbuYJZuJfh1fAXPhBuoEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}